Control device for switched reluctance motor

Abstract

A control device for a switched reluctance motor includes an inverter having a switching circuit that switches a magnetic pole to provide a first winding pattern or a second winding pattern. With respect to a boundary dividing a driving range of the switched reluctance motor into two ranges, the control device performs switching to the first winding pattern when the torque and the rotational speed are located in the first range on the low load side, performs switching to the second winding pattern when the torque and the rotational speed are located in the second range, allows switching of the magnetic pole in a case where a current of the phase whose magnetic pole is to be switched among the three-phase coils is 0, and prohibits switching of the magnetic pole in a case where the current of the phase whose magnetic pole is to be switched is not 0.

What is claimed is: 
     
       1. A control device for a switched reluctance motor, the switched reluctance motor being configured to be driven when excitation currents flow through three-phase coils of the switched reluctance motor, the control device comprising:
 an inverter including a switching circuit configured to switch a magnetic pole to provide a first winding pattern or a second winding pattern by changing a direction of current that flows in at least one phase of the three-phase coils, the first winding pattern being a winding pattern in which the three-phase coils are wound in the same direction, the second winding pattern being a winding pattern in which the two coils of the three-phase coils are wound in the same direction, the remaining one coil is wound in an opposite direction, and the two coils with the same winding direction and the one coil with the opposite winding direction are alternately arranged; and 
 an electronic control unit configured to: 
 with respect to a boundary dividing a driving range of the switched reluctance motor into a first range and a second range, the driving range determined by a torque and a rotational speed of the switched reluctance motor, 
 (i) switch the magnetic pole by the switching circuit so as to provide the first winding pattern when the torque and the rotational speed that are determined according to an applied voltage are located in the first range on a low load side; 
 (ii) switch the magnetic pole by the switching circuit so as to provide the second winding pattern when the torque and the rotational speed that are determined according to the applied voltage are located in the second range different from the first range; 
 (iii) allow switching of the magnetic pole in a case where a current of the phase whose magnetic pole is to be switched among the three-phase coils is 0 when switching the magnetic pole by the switching circuit; and 
 (iv) prohibit switching of the magnetic pole in a case where the current of the phase whose magnetic pole is to be switched is not 0. 
 
     
     
       2. The control device according to  claim 1 , wherein
 the electronic control unit is configured to: 
 (i) switch between intermittent current control in which there is a period where a current that flows through each of the three-phase coils becomes 0, and continuous current control in which there is no period where a current that flows through each of the three-phase coils becomes 0, according to the torque and the rotational speed of the switched reluctance motor; and 
 (ii) perform the switching from the intermittent current control to the continuous current control after the magnetic pole is switched by the switching circuit, when the electronic control unit switches the magnetic pole by the switching circuit after switching from the intermittent current control to the continuous current control. 
 
     
     
       3. The control device according to  claim 1 , wherein
 the second range when the voltage applied to the switched reluctance motor is low is wider than the second range when the voltage applied to the switched reluctance motor is high. 
 
     
     
       4. The control device according to  claim 1 , wherein
 a deadband in which switching between the first winding pattern and the second winding pattern is not performed is provided at the boundary between the first range and the second range. 
 
     
     
       5. The control device according to  claim 1 , wherein
 the inverter includes switching circuits for a plurality of phases.